1 66 THE STEM PROPER 



WOOD STRUCTURE 



Material. — Select from the billets of wood cut for the fire, 

 sticks of various kinds ; hickory, ash, oak, chestnut, maple, walnut, 

 cherry, pine, cedar, tulip tree, all make good specimens. Red oak 

 shows the medullary rays particularly well. Get sticks of green wood 

 if possible and have them planed smooth at the ends. It would be 

 well for the teacher to have a hatchet and let the class collect their 

 own specimens. Collect also, where they can be obtained, waste bits of 

 dressed lumber from a carpenter or joiner. For city schools prepared 

 samples should be obtained of the dealers. If nothing better is avail- 

 able, any pieces of unpainted woodwork about the schoolroom will 

 furnish subjects for study. 



309. — Cross section through a black oak, showing heartwood and sapwood 

 (from PINCHOT, U. S. Dept. of Agr.). 



235 . Detailed Structure of a Woody Stem. — Select a good- 

 sized billet of hard wood and count the rings of annual 

 growth. How old was the tree or the bough from which 

 it was taken ? Was its growth uniform from year to year .'' 

 How do you know ? Are the rings broadest, as a general 

 thing, toward the center or the circumference ? How do 



